1. Field of the Invention
The present invention relates to an optical film, a barrier film, a light conversion member, a backlight unit, and a liquid crystal display device. More specifically, the present invention relates to an optical film, a barrier film using the optical film, a light conversion member using the optical film or the barrier film, a backlight unit using the light conversion member, and a liquid crystal display device using the backlight unit.
2. Description of the Related Art
A flat panel display such as a liquid crystal display device (hereinafter, also referred to as LCD) has been variously used annually as a space saving image display device having low power consumption. The liquid crystal display device, for example, is configured by disposing backlight (hereinafter, also referred to as BL), a backlight side polarizing plate, a liquid crystal cell, a visible side polarizing plate, and the like in this order.
In the recent flat panel display market, power saving, high definition, and improvement in color reproducibility have progressed as enhancement in LCD performance, and in particular, the progress of the enhancement in LCD performance is remarkable in a small-size display of a tablet PC, a smart phone, or the like, and a next-generation hi-vision (4K2K, an EBU ratio of greater than or equal to 100%) of the current TV standard (FHD, a national television system committee (NTSC)) ratio of 72%≅ an European broadcasting union (EBU) ratio of 100%) has been developed. However, in order to supply the next-generation hi-vision to the market, a cost reduction according to a reduction in the number of members by further performing functional integration of the members is essential.
A method of increasing light utilization efficiency of the backlight which is necessary for the power saving has been examined. For example, in JP2012-169271A, a method is disclosed in which a quantum dot (hereinafter, also referred to as QD and a quantum dot) emitting red light and green light is used between a blue LED and a light guide plate as a fluorescent body, and white light is embodied by emitting RGB bright line light (blue light, green light, and red light having a small full width at half maximum), and thus high brightness and improvement in color reproducibility are realized.
In SID'12 DIGEST p. 895, a method of combining a light conversion sheet (QDEF) using a quantum dot for enhancing color reproducibility of the LCD is proposed.
In addition, in an optical film member used in the liquid crystal display device, study of increasing transmittance in order to increase light utilization efficiency has been examined. For example, in JP2005-96108A, a method is proposed in which high total light transmittance and high barrier properties are compatible with each other by adjusting a film thickness of each layer of a barrier film which is used in an optical member of FPD or the like and includes a substrate, a first inorganic layer, an organic film, and a second inorganic film in this order.
Furthermore, an example is known in which the barrier film is laminated on the light conversion sheet using the quantum dot even though this example does not directly indicate enhancement in the light transmittance (refer to US2012/0113672A).